Screen for guided missiles to inhibit spurious responses



Dec. 20, 1966 T. G. B. BOYDELL 3,293,437

SCREEN FOR GUIDED MISSILES TO INHIBIT SPURIOUS RESPONSES 4 Sheets-Sheet1 Filed June 50, 1959 v10f/ 6 J3. [305490 17% vh -v a/ Dec. 20, 1966BOYDELL 3,293,437

SCREEN FOR GUIDED MISSILES TO INHIBIT SPURIOUS RESPONSES 4 Sheets-Sheet2 Filed June 50, 1959 Dec. 20, 1966 T. G. B. BOYDELL 3,293,437

SCREEN FOR GUIDED MISSILES T0 INHIBIT SPURIOUS RESPONSES Filed June 30,1959 4 Sheets-Sheet :5v

: D 0, 1966 T. e. B. BOYDELL Y 3,293,437

SCREEN FOR GUIDED MISSILES TO INHIBIT SPURIOUS RESPONSES Filed June 30,1959 4 Sheets-Sheet 4.

that/1:7 G: -5374? United States Patent ice 3,293,437 SCREEN FUR GUIDEDMISSILES TO INHHBHT SPURTGUS RESPONSES Timothy Gordon Bevan Boydeil,Heaton, Bolton Lancashire, England, assignor to Hawker Siddeley DynamicsLimited, Hatfield, England Fiied June 30, N59, Ser. No. 824,137 Claimspriority, applicadon Great Britain, July 1, 1958, 2ll,122/58 9 Claims.(Cl. 12.50-83.35)

This invention relates to guided missiles, the missle to which thepresent'invention is applied including a homing head consisting of atransparent nose piece through which infra-red radiations from thetarget are optically projected into a sensing system which centralisesthe target in the field of view and indirectly operates the controlsurfaces of the missile to thereby bring and maintain the missile ontarget. The transparent nose piece although of any suitable shape, ispreferably built up of a plurality, for example, eight, optically flattransparent segments, the nose being therefore of octagonal pyramidshape.

The invention, although applicable to surface to air guided missiles isparticularly applicable to guided missiles of the air to air type whichare intended to be carried by and released from aircraft and aredirected against aircraft targets.

It will be appreciated that for such a missile to operate efficiently,the missile must be so designed that it will reject spurious targets asfar as possible and faithfully follow the movements of the target in thefield of view.

The acceptance angle or field of view of the sensing system must,therefore, be a compromise between a very small angle which wouldnecessitate a very careful initial aiming of the missile at the targetand might also result in the loss of the target from the field of view,and a large angle which would include spurious targets which would beliable to adversely affect the missiles operational efiiciency.

In order to increase the field covered by the sensing system, this ismounted on a gymbal system which enables it to scan over a much largersolid angle than that which it covers instantaneously. The area coveredby the permitted angular movements of the sensing system is called thefield of look.

It will be appreciated, therefore, that it is desirable to exclude asfar as possible spurious targets from the field of look.

Spurious targets may be grouped into three distinct classes, namely,enemy counter-measures, clouds and the sun.

The present invention is concerned with the elimination of spurioustargets in the third group, namely, solar radiations which do not passdirectly into the sensing system but take the form of reflections fromthe inner surfaces of the transparent nose piece.

Instructions given to the pilot of the missile-carrying aircraftpreclude the firing of the missile when the sun is in a position whereit can be seen directly by the sensing system.

The invention consists broadly in providing the homing head with aninternally positioned screen which will protect the sensing system fromsolar or other spurious target radiations which might otherwise bereflected off the internal surfaces of the transparent nose into thesensing system.

With such an arrangement, direct radiations from the target, when thelatter is situated within the field of look will pass directly into thesensing system, provided this is suitably orientated, but reflectionswhich might accidentally reach the sensing system and emanating from thesun or other spurious targets lying outside the field of 3,293,437Patented Dec. 26, 1966 look will be intercepted and prevented fromreaching the sensing system.

Referring to the accompanying drawings:

FIGURE 1 is a perspective view partly in section illustrating a hominghead for a guided missile incorporating an internally positioned screenin accordance with the present invention;

FIGURE 2 is a longitudinal sectional view illustrating the manner inwhich the screen operates to intercept solar or other spurious targetradiations;

FIGURE 3 is a side elevation partly in section of the screen removed;

FIGURE 4 is a front elevation; it

FIGURE 5 is an exploded view illustrating the screen components and itswire support;

FIGURE 6 is a fragmentary front elevation of the screen support; and

FIGURE 7 is a side elevation of the same.

FIGURES l and 2 illustrate the main constructional parts of the hominghead. The sensing system is indicated generally by reference numeral 1,the sensing system being in the form of a unit mounted on gymbals 2 and3 so that it will have a limited universal angular movement, the sensingsystem including a sensing head 4, the area covered by the sensing headas a result of the permitted angular movement of the sensing systembeing referred to as the field of look, this angular movement of thesensing system being clearly depicted in FIGURE 2.

The sensing head is of conventional arrangement and includes an annularprimary reflective surface (FIGURE 1) which receives radiations fallingon it in directions parallel, or nearly so, to the axis of the sensinghead normal to the surface. Such radiations are reflected on to asecondary reflective surface facing and spaced from the primary surfaceand again reflected through a cylindrical barrel into the sensing headfor detection. The sensing head is indirectly connected to controlsurfaces of the missile to effect control thereof.

The field of acceptance is the space around the axis of the sensinghead, within which radiations fall directly on the primary surface. Ifthe sensing head has its axis pointed at, or within a predeterminedangle of, a target then direct radiations fall upon the primary surfaceand are reflected into the sensing system. This is because the target iswithin the field of acceptance. As the sensing head is mounted ingymbals, its axis movable within a field of look and a target within thefield of look will have its radiations received when the axis of thesensing head is so orientated within the field of look that the targetis within the field of acceptance.

The control surfaces of the missile are so controlled as to bring themissile into a position in which the axis of the sensing head iscentralised on the missile axis when the target is in the field ofacceptance, that is when the sensing head is looking at the target. Thelimits of the field of acceptance are set by conventional cylindricallight stops or baflies.

The sensing system is contained within the forward part of the casing 5of the missile, the casing carrying at its forward end a transparentnose piece of octagonal pyramid shape and built up from eight opticallyflat transparent segments 6.

If the sensing head is not orientated to look at the target, directradiations close to but not within the field of acceptance are preventedfrom entering the sensing system in conventional manner by the lightstops or baffles. However it is also important to prevent radiationsfrom outside the field of acceptance entering, through the fiat segments6, the space within and being reflected by the internal surfaces of thesegments until they are apparently within the field of acceptance beingparallel or nearly so, to the axis of the sensing head 4 in one of itspositions 3 of orientation in the field of look (FIGURE 2). Suchradiations would, if not stopped, be received into the sensing systemand give the impression that the sensing head was looking at a target.

Contained within the nose piece is a screen indicated generally byreference numeral 7 the positioning of the screen Within the nose piecebeing clearly shown in FIGURES 1 and 2.

The screen as shown in detail in the remaining figures is built up froma series of metal blanks which are blackened to prevent reflections fromtheir surfaces even at oblique angles, the screening system being soconstructed and arranged that whilst effectively preventing spurioussolar images indirectly reaching the sensing system, it presents theminimum amount of obstruction to target radiation for all possibletarget positions.

The screen fits closely within the transparent nose piece and in thecase of an octagonal nose piece as illustrated the screen includes twomain vanes 8 and 9 which intersect -at right angles, vane 8 being formedwith a centrally positioned longitudinally arranged slot 10 and vane 9with a co-operating slot 11 thus enabling the vanes to be assembledtogether at right angles.

Subsidiary vanes 12 and 13 of shorter length again formed withinterengaging slots are provided which enter at their points ofintersection slots 14 and 15 formed in vanes 8 and 9 and lie in planessituated at 45 to the planes containing vanes 8 and 9, the outer edgesof the vanes engaging the transparent segments of the nose piece attheir points of intersection.

Surrounding vanes 12 and 13 is an additional screen or shroud 16 ofoctagonal shape which may conveniently be bent up from a single blank ofsheet metal, the ends being rivetted together as at 17.

The walls of the additional screen 16 taper rearwardly, the rear edge ofthe additional screen being notched at 18 to receive the hooked ends 19of a wire screen support including eight resilient wire arms 20 weldedto an annular wire ring 21, the wire support locating the screen snuglyin position within the transparent nose piece. The arms 20 normallyoccupy the position shown by full lines in FIGURE 7 but may be sprunginwardly into the dotted line position to engage the notches.

The operation of the screen to intercept spurious target radiations isshown clearly in FIGURE 2.

The sensing head is shown by full lines in an intermediate positionwithin its range of angular movement and by dotted lines in its extremeposition in one direction.

Spurious target radiations are shown in full and dotted lines andindicated by reference letters R and reflected images are shown bydotted lines and indicated by reference letters Rl.

It will be seen that all the direct and reflected spurious targetradiations R and R1 which would come within the field of look of thesensing system are effectively intercepted by the various opaquenon-reflecting parts of the screen, the screen fitting closely withinthe octagonal nose piece as shown clearly in FIGURE 2.

The screen is supported at its forward end by a centrally positionedspigot 22 formed with slots which intersect at right angles and areintended to receive the eX- tremities of vanes 8 and 9.

I claim:

1. In a guided missile including a homing head containing a sensingsystem sensitive to heat radiations emanating from a target andangularly movable to cover a predetermined field of look, the missilehaving a transparent nose piece through which the said radiations canpass into the sensing system, a screen adapted to fit closely within thelength and breadth of the nose piece of opaque non-reflective materialand radiating outwardly from a center line in the form of a cross, saidscreen comprising two substantially polygonal blanks, said blanks beingformed of two similar substantially triangular portions,

I a forward elongated, substantially triangular, tapered portion and arearward truncated triangular portion, and subsidiary screens of opaquenon-reflective material disposed between the rearward ends of saidblanks adjacent the truncated triangular portion.

2. A screen as claimed in claim 1, including a shroud enclosing the twosets of blanks at their rearward ends.

3. A screen as claimed in claim 1, wherein the outer edges of the blanksat their rearward ends taper rearwardly and are enclosed by a shroud inthe form of a multi-sided rearwardly tapering ring.

4. A screen as claimed in claim 1, positioned at its rearward end insaid nose piece by a wire support in the form of a ring having a seriesof forwardly directed resilient wire arms adapted to engage thecomposite screen at its rear end.

5. In a guidedrnissile including a homing head containing a sensingsystem sensitive to heat radiations emanating from a targetand'angularly movable to cover a predetermined field of look, themissile having a transparent nose piece through which the saidradiations can pass into the sensing system, a screen adapted to fitclosely within the length and breadth of the nose piece of opaquenon-reflective material and radiating outwardly from a center line inthe form of a cross, said screen comprising two substantially polygonalblanks, said blanks being formed of two similar substantially triangularportions, a forward elongated, substantially triangular, tapered portionand a rearward truncated triangular portion, the outer edges of theblanks at their rearward ends tapering rearwardly and being enclosed bya shroud in the form of a multi-sided, rearwardly tapering ring.

6. A screen as claimed in claim 5, positioned at its rearward end insaid nose piece by a wire support in the form of a ring having a seriesof forwardly directed resilient wire arms adapted to engage thecomposite screen at its rear end.

7. A screen as claimed in claim 3, positioned at its rearward end insaid nose piece by a wire support in the form of a ring having a seriesof forwardly directed resilient wire arms adapted to engage thecomposite screen at its rear end.

8. In a guided missle including a homing head containing a sensingsystem sensitive to heat radiations emanating from a target andangularly movable to cover a predetermined field of look, the missilehaving a transparent nose piece through which the said radiations canpass into the sensing system, a screen adapted to fit closely within thelength and breadth of the nose piece of opaque non-reflective materialand radiating outwardly from a center line in the form of -a cross, saidscreen comprising two substantially polygonal blanks, said blanks beingformed of two similar substantially triangular portions, a forwardelongated, substantially triangular, tapered portion and a rearwardtruncated triangular portion, said screen being positioned at itsrearward end in said nose piece by a wire support in the form of a ringhaving a series of forwardly directed resilient wire arms adapted toengage the composite screen at its rear end.

9. In a guided missile including a homing head containing a sensingsystem sensitive to heatradiations emanating from a target and angularlymovable to cover a predetermined field of look, the missile having atransparent nose piece through which the said radiations can pass intothe sensing system, a screen adapted to fit closely within the lengthand breadth of the nose piece, of opaque non-reflective material andradiating outwardly from a center line in the form of a cross, saidscreen being built up of vanes of opaque, non-reflective materialcomprising two main flat vanes intersecting at right angles and twoshorter vanes also intersecting at right angles and arrangedintermediate the main vanes, the main vanes and shorter vanes beingenclosed at the rear end of the screen by a shroud in the form of anoctagonal, rearwardly tapering ring.

(References on following page) References Cited by the Examiner UNITEDSTATES PATENTS 6 FOREIGN PATENTS 348,409 5/1937 Italy.

RALPH G. NILSON, Primary Examiner.

CHESTER L. IUSTUS, Examiner.

D. G. BREKKE, R. A. FARLEY, M. R. WILBUR,

M. ABRAMSON, Assistant Examiners.

1. IN A GUIDED MISSILE INCLUDING A HOMING HEAD CONTAINING A SENSINGSYSTEM SENSITIVE TO HEAT RADIATIONS EMANATING FROM A TARGET ANDANGULARLY MOVABLE TO COVER A PREDETERMINED FIELD OF LOOK, THE MISSILEHAVING A TRANSPARENT NOSE PIECE THROUGH WHICH THE SAID RADIATIONS CANPASS INTO THE SENSING SYSTEM, A SCREEN ADAPTED TO FIT CLOSELY WITHIN THELENGTH AND BREADTH OF THE NOSE PIECE OF OPAQUE NON-REFLECTIVE MATERIALAND RADIATING OUTWARDLY FROM A CENTER LINE IN THE FORM OF A CROSS, SAIDSCREEN COMPRISING TWO SUBSTANTIALLY POLYGONAL BLANKS, SAID BLANKS BEINGFORMED OF TWO SIMILAR SUBSTANTIALLY TRIANGULAR PORTIONS, A FORWARDELONGATED, SUBSTANTIALLY TRIANGULAR, TAPERED PORTION AND A REARWARDTRUNCATED TRIANGULAR PORTION, AND SUBSIDIARY SCREENS OF OPAQUENON-REFLECTIVE MATERIAL DISPOSED BETWEEN THE REARWARD ENDS OF SAIDBLANKS ADJACENT THE TRUNCATED TRIANGULAR PORTION.